Most of the volumes of the series "Su"?wasserflora von Mitteleuropa" are written in German language, the volumes 2/1 - 2/4 dealing with the Bacillariophyceae (diatoms) as well. They enable the user to identify all diatom-species and provide him with the taxonomic and ecological information.Since the number of the known diatoms-taxa has increased considerably it is extremely important to distinguish the different species. This was until now restricted to the limnologists, biologists and geographers capable of understanding the German language.This additional volume 2/5 presents all the dichotom keys from the Bacillariophyceae-volumes 2/1 - 2/4 in English and French translation. They user can work through the key, identify the species and then - if necessary - gather the further information from the German volumes.